• Proceedings of the KWS Conference
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• 2004.05a
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• pp.321-323
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• 2004

전자 제품에 사용되는 부품 ㆍ소재의 신뢰성 품질 평가를 위해 정밀한 모터의 제어기술, 첨단신호처리 기술, 압전소자 기술의 발달로 미세변화 계측의 재현성, 고분해능, 표면과 내부의 이미지관찰, 또한 미소부위에서 재료의 누설탄성표면파의 음속측정이 가능한 초음파현미경에 대한 연구가 최근 들어 활발히 진행되고 있다. (중략)

• Proceedings of the KWS Conference
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• 1995.10a
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• pp.165-169
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• 1995

This paper deals with determining the proper friction welding condition and analyzing mechanical in of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch), the alloy steel to aluminum(A6061 for the interlayer material between the blade part and the shank) and sintered carbide tool materials to aluminum. And also acoustic emission test will be carried out during fiction welding to evaluate the weld quality.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.184-186
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• 2001

Quality estimation of the weld has been one of the important issues in RSW which is a main process of the sheet metal fabrication in auto-body industry. It was well known that among the various welding process variables, dynamic resistance has a close relation with nugget formation. In this study, a new quality estimation algorithm is developed with the primary dynamic resistance measured at welding machine timer. For this, Back propagation algorithm of neural network is used.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.4
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• pp.511-519
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• 1996

The purposes of this study are 1) to develop optimum FRW technique of SNCM220, SCM435, SACM645 and SCM415 bar-to-bar similar friction welding, 2) to develop in-process real-time weld quality nondestructive evaluation technique by acoustic emission method, and 3) to certify of weld quality by inspection of tensile fracture surface on friction welded joints.

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.334-339
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• 2019

In this study, the vibration test method to nondestructively evaluate the possibility of vehicle BSR (Buzz, Squeak, Rattle) noise generation in spot-welded structures was proposed. The weld quality was predicted by analyzing the local vibration transmission characteristics for the beam-shaped structure attached to testing spots. The bending stiffness was evaluated from the identified vibration properties. From the change in the stiffness, the weld quality was evaluated. For verification of the proposed method, the welded specimens were fabricated with partial changes in welding parameters. The local vibration transfers were measured. The frequency bands affected by the weld quality was identified. The capability of evaluating the welding parameters including defect position and quality variations was investigated. The proposed method enables fast quality evaluation to minimize the possibility of BSR noise generation in the manufactured vehicle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.605-610
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• 2008

Through welding fabrication, user can feel unsatisfaction of surface quality because of welded defects, Generally speaking, these are called weld defects. For checking these defects effectively without time loss effectively, weldability estimation system setup is an urgent thing for detecting whole specimen quality. In this study, by laser vision camera, catching a rawdata on welded specimen profiles, treating vision processing with these data, qualitative defects are estimated from getting these information at first. At the same time, for detecting quantitative defects, whole specimen weldability estimation is pursued by multifeature pattern recognition, which is a kind of fuzzy pattern recognition. For user friendly, by weldability estimation results are shown each profiles, final reports and visual graphics method, user can easily determined weldability. By applying these system to welding fabrication, these technologies are contribution to on-line weldability estimation.

• Journal of Welding and Joining
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• v.12 no.2
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• pp.97-107
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• 1994

Both in-process quality control and high reliability of the weld is one of the major concerns in applying friction welding to the economical and qualified mass-production. No reliable nondestructive monitoring method is available at present to determine the real-time evaluation of automatic production quality control for friction welding of special hydraulic valve spool of 16mm in diameter. This paper, so that, presents the experimental examinations and statistical quantitative analysis of the correlation between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation periods of the welding and the tensile strength and other properties of the welded joints of $\phi16$ valve spool as well as the various welding variables, as a new approach which attempts finally to develop real-time quality monitoring system for friction welding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6282-6288
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• 2014

$CO_2$ welding is used widely in the field. On the other hand, welding defects occur when welders cannot adjust the current and voltage needed for welding and have to stop working to adjust the current and voltage, causing sudden cooling down of the welding structure inside a vehicle or tank where the control panel is invisible or when work site is far. This study used three types of existing $CO_2$ welders. This also applied SS400 rolled steel for welding structural purposes for remote control torch welding, perform a welding test through v-groove butt welding with a remote control torch and existing $CO_2$ welding torch, conducted visual inspection on the appearance of a welded top bead. In addition, the appearance quality of the welding part was monitored mainly through penetrant testing and a bending test to evaluate the welding defect reduction and the effect on the performance and compatibility by replacing the existing welder.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.120-120
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• 2009

스테인리스강은 내식성이 우수하여 열교환기, 화학플랜트 등 부식환경의 구조물 혹은 파이프에 널리 사용되고 있다. 스테인리스 파이프 제조에 사용되는 용접방법은 주로 GTA 용접이 적용되고 있는데, 이 방법은 용접부 품질은 우수하지만 용접 생산성이 늦은 단점이 있다. 또한 이상스테인리스 등과 같은 특수한 용도의 스테인리스 강은 기존의 용접으로는 용접부 성능 확보가 어렵다. 레이저는 고밀도로 집속되고 직진성이 우수한 일종의 빛으로 용접/절단 등 금속 혹은 비금속의 가공에 널리 사용되고 있다. 레이저 용접의 장점은 비접촉으로 용접이 가능하고, 용접 속도가 매우 빠르고, 용접이 가능한 소재의 종류 혹은 두께의 제약이 적고, 용접부가 작아 변형이 적다는 것이다. 이러한 장점으로 인하여 자동차산업에 적용이 급격히 증가하였으며, 최근에는 다양한 분야에 적용이 추진되고 있다. 본 발표에서는 스테인리스강의 파이프 제조 공정에 레이저용접을 적용하기 위한 기초 연구를 수행하였다. 사용된 소재는 오스테나이트계 및 이상스테인리스강이었으며, 용입특성, 용접부 기계적 특성 등을 알아 보았으며, 열처리에 따른 특성 변화를 평가하였다.

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.318-321
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• 2001

클래딩은 주요 산업분야에 내마모성, 내부식성의 향상을 위해 사용되고 있다. 그러나 클래딩 공정에서는 모재와 클래딩 재료의 물리적, 화학적 특성의 차이와 여러 가지 공정 변수의 영향으로 제품의 사용에 치명적인 손상을 줄 수 있는 균열, 슬래그 개재물, 기공등의 불연속이 발생하기 쉽다. 본 연구에서는 클래딩 시에 발생되는 불연속을 실시간으로 검출하는데 아주 우수한 검출능력을 갖고 있는 비파괴 검사 방법인 음향방출시험을 적용하고 검출된 신호에 대한 주파수 분석과 2차원 위치표정을 실시하여 균열, 기공 등의 불연속을 검출하였고 이를 주사전자현미경을 통하여 확인하였다. 음향방출법에 의해 클래딩부에서 발생하는 결함에 대한 실시간 평가가 가능함을 입증하였으며, 특히 다층 클래딩이나 넓은 면적의 클래딩시에 불연속을 가장 신속하게 감지할 수 있으므로 이를 생산공정에 활용한다면 클래딩 또는 용접부 품질감시를 위한 효과적인 방법이 될 것이다.